Enquanto combate Kiyama, que se recusa a ceder o controlo da rede Upper Level, Misaka tem visões sobre aquilo que a levou a criar a referida rede.

Misaka tenta travar o ser que emergiu de Kiyama, mas as suas investidas só o tornam mais forte. A descontrolada rede Level Upper atormenta os seus utilizadores.

Tsukuyomi cria uma disciplina para antigos utilizadores da Level Upper, para os ajudar a perceber que o verdadeiro potencial só se alcança através da realidade.

Misaka mostra o espaço do festival às suas convidadas, Saten and Uiharu, e prepara-se para a sua muito aguardada atuação.

Uiharu recebe Haruue, uma nova companheira de quarto, ao mesmo tempo que o campus é abalado por uma misteriosa e potencialmente perigosa atividade poltergeist.

Quando a identidade de Therestina é revelada, Kongou impede Misaka de a combater sozinha, e as duas reúnem as amigas para salvarem os prisioneiros de Therestina.

As espers escapam a uma emboscada e tentam travar Therestina antes que ela cumpra os seus planos de fazer Haruue evoluir para o nível 6, para destruir a Cidade Académica.

Haru'ue joins Saten and Uiharu on a trip to the Garden of Learning to see Misaka and Shirai, as well as to do some shopping. They later go to visit Edasaki in the hospital, where she is undergoing physical therapy, when things take an unexpected twist.

Febri takes an instant liking to Saten, and is warm to everyone except for Misaka, much to her chagrin. At Judgment, Uiharu is unable to find any information on who Febri is, so arrangements are made to admit her into an orphanage as a "Child Error."

As Yomikawa takes over investigating the runaway security robots, Konori invites the whole gang out to take in a bath at a bathhouse. On their way home, a number of detours lead them to a confrontation with yet another, much more dangerous runaway robot.

With the revelation that Febri is synthetic, Misaka is determined to find whoever built her, and have them fix her. The investigation is stalled on all fronts, even with the help of her friends running down leads, until help comes from a surprise source.

Aritomi reveals his motivations for STUDY's project to Misaka. She also learns about Nunotaba's plight, and some of the details concerning what STUDY has planned at the Reach Assembly the next day. Will she be able to escape and put a stop them?

Shirai, Konori, Kongo and friends, and Uiharu and Saten confront the powered suits at the four Assembly sites, where they soon receive backup. Misaka and Febrie move to take on Aritomi directly, but he has one final surprise up his sleeve for them.